Improved AlGaN/GaN Metal-Oxide-Semiconductor High-Electron Mobility Transistors With TiO2 Gate Dielectric Annealed in Nitrogen

An AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) that uses a high-k TiO2 gate insulator is demonstrated. TiO2 films are annealed at 300 degrees C and 600 degrees C in N-2 or O-2 following the deposition of an oxide layer. Experimental results reveal that the 300 degrees C N-2-annealed TiO2/GaN MOS capacitor has the smallest interface traps of any of the studied devices. The 300 degrees C N-2-annealed oxide interlayers between the GaN and the gate metal reduce the gate leakage current and improve the dc, high-frequency, and noise characteristics. The gate leakage current of the 300 degrees C N-2-annealed MOS-HEMT is more than 3 orders of magnitude less than that of the baseline HEMT. This brief is the first to fabricate a GaN-based MOS-HEMT using an N-2-annealed TiO2 gate insulator.